SDIO出错 error -84 sending status command, retrying end_request: I/O error, dev mmcblk0, sector
在调试emmc的时候遇到一个问题，挂载emmc出现如下错误：
~ # mount /dev/mmcblk0 /mnt/
end_request: I/O error, dev mmcblk0, sector 2EXT4-fs (mmcblk0): unable to read superblock
mmcblk0: error -84 sending status command, retrying
mmcblk0: error -84 sending stop command, original cmd response 0x900, card status 0x900
mmcblk0: error -84 transferring data, sector 0, nr 8, cmd response 0x900, card status 0x100
mmcblk0: retrying using single block read
mmcblk0: error -84 sending status command, retrying
mmcblk0: error -84 sending status command, retrying
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: error -84 sending status command, retrying
mmcblk0: error -84 transferring data, sector 0, nr 2, cmd response 0x900, card status 0x0mmcblk0: retrying using single block read
虽然有错误，但是挂载应该是成功了。我在挂载前，在mnt目录下建了一个文件，挂载后文件没了，用df -h 查看磁盘的状态，也有报错。
/mnt/bin # df -h
Filesystem Size Used Available Use% Mounted on
/dev/root 32.0M 12.8M 19.2M 40% /
tmpfs 13.1M 4.0K 13.1M 0% /dev
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: error -84 sending status command, retrying
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
end_request: I/O error, dev mmcblk0, sector 1798
end_request: I/O error, dev mmcblk0, sector 1799
end_request: I/O error, dev mmcblk0, sector 1800
end_request: I/O error, dev mmcblk0, sector 1801
end_request: I/O error, dev mmcblk0, sector 1802
end_request: I/O error, dev mmcblk0, sector 1803
end_request: I/O error, dev mmcblk0, sector 1804
end_request: I/O error, dev mmcblk0, sector 1805
end_request: I/O error, dev mmcblk0, sector 1806
end_request: I/O error, dev mmcblk0, sector 1807
end_request: I/O error, dev mmcblk0, sector 1808
end_request: I/O error, dev mmcblk0, sector 1809
end_request: I/O error, dev mmcblk0, sector 1810
end_request: I/O error, dev mmcblk0, sector 1811
end_request: I/O error, dev mmcblk0, sector 1812
end_request: I/O error, dev mmcblk0, sector 1813
end_request: I/O error, dev mmcblk0, sector 1814
end_request: I/O error, dev mmcblk0, sector 1815
end_request: I/O error, dev mmcblk0, sector 1816
end_request: I/O error, dev mmcblk0, sector 1817
end_request: I/O error, dev mmcblk0, sector 1818
end_request: I/O error, dev mmcblk0, sector 1819
end_request: I/O error, dev mmcblk0, sector 1820
end_request: I/O error, dev mmcblk0, sector 1821
end_request: I/O error, dev mmcblk0, sector 1822
end_request: I/O error, dev mmcblk0, sector 1823
end_request: I/O error, dev mmcblk0, sector 1824
end_request: I/O error, dev mmcblk0, sector 1825
end_request: I/O error, dev mmcblk0, sector 1826
end_request: I/O error, dev mmcblk0, sector 1827
end_request: I/O error, dev mmcblk0, sector 1828
end_request: I/O error, dev mmcblk0, sector 1829
end_request: I/O error, dev mmcblk0, sector 1830
end_request: I/O error, dev mmcblk0, sector 1831
end_request: I/O error, dev mmcblk0, sector 1832
end_request: I/O error, dev mmcblk0, sector 1833
end_request: I/O error, dev mmcblk0, sector 1834
end_request: I/O error, dev mmcblk0, sector 1835
end_request: I/O error, dev mmcblk0, sector 1836
end_request: I/O error, dev mmcblk0, sector 1837
end_request: I/O error, dev mmcblk0, sector 1838
end_request: I/O error, dev mmcblk0, sector 1839
end_request: I/O error, dev mmcblk0, sector 1840
end_request: I/O error, dev mmcblk0, sector 1841
end_request: I/O error, dev mmcblk0, sector 1842
end_request: I/O error, dev mmcblk0, sector 1843
end_request: I/O error, dev mmcblk0, sector 1844
end_request: I/O error, dev mmcblk0, sector 1845
end_request: I/O error, dev mmcblk0, sector 1846
end_request: I/O error, dev mmcblk0, sector 1847
end_request: I/O error, dev mmcblk0, sector 1848
end_request: I/O error, dev mmcblk0, sector 1849
end_request: I/O error, dev mmcblk0, sector 1850
end_request: I/O error, dev mmcblk0, sector 1851
end_request: I/O error, dev mmcblk0, sector 1852
end_request: I/O error, dev mmcblk0, sector 1853
end_request: I/O error, dev mmcblk0, sector 1854
end_request: I/O error, dev mmcblk0, sector 1855
end_request: I/O error, dev mmcblk0, sector 1856
end_request: I/O error, dev mmcblk0, sector 1857
end_request: I/O error, dev mmcblk0, sector 1858
end_request: I/O error, dev mmcblk0, sector 1859
end_request: I/O error, dev mmcblk0, sector 1860
end_request: I/O error, dev mmcblk0, sector 1861
end_request: I/O error, dev mmcblk0, sector 1862
end_request: I/O error, dev mmcblk0, sector 1863
end_request: I/O error, dev mmcblk0, sector 1864
end_request: I/O error, dev mmcblk0, sector 1865
end_request: I/O error, dev mmcblk0, sector 1866
end_request: I/O error, dev mmcblk0, sector 1867
end_request: I/O error, dev mmcblk0, sector 1868
end_request: I/O error, dev mmcblk0, sector 1869
end_request: I/O error, dev mmcblk0, sector 1870
end_request: I/O error, dev mmcblk0, sector 1871
end_request: I/O error, dev mmcblk0, sector 1872
end_request: I/O error, dev mmcblk0, sector 1873
end_request: I/O error, dev mmcblk0, sector 1874
end_request: I/O error, dev mmcblk0, sector 1875
end_request: I/O error, dev mmcblk0, sector 1876
end_request: I/O error, dev mmcblk0, sector 1877
end_request: I/O error, dev mmcblk0, sector 1878
end_request: I/O error, dev mmcblk0, sector 1879
end_request: I/O error, dev mmcblk0, sector 1880
end_request: I/O error, dev mmcblk0, sector 1881
end_request: I/O error, dev mmcblk0, sector 1882
end_request: I/O error, dev mmcblk0, sector 1883
end_request: I/O error, dev mmcblk0, sector 1884
end_request: I/O error, dev mmcblk0, sector 1885
end_request: I/O error, dev mmcblk0, sector 1886
end_request: I/O error, dev mmcblk0, sector 1887
end_request: I/O error, dev mmcblk0, sector 1888
end_request: I/O error, dev mmcblk0, sector 1889
end_request: I/O error, dev mmcblk0, sector 1890
end_request: I/O error, dev mmcblk0, sector 1891
end_request: I/O error, dev mmcblk0, sector 1892
end_request: I/O error, dev mmcblk0, sector 1893
end_request: I/O error, dev mmcblk0, sector 1894
end_request: I/O error, dev mmcblk0, sector 1895
end_request: I/O error, dev mmcblk0, sector 1896
end_request: I/O error, dev mmcblk0, sector 1897
end_request: I/O error, dev mmcblk0, sector 1898
end_request: I/O error, dev mmcblk0, sector 1899
end_request: I/O error, dev mmcblk0, sector 1900
end_request: I/O error, dev mmcblk0, sector 1901
end_request: I/O error, dev mmcblk0, sector 1902
end_request: I/O error, dev mmcblk0, sector 2051
end_request: I/O error, dev mmcblk0, sector 2052
end_request: I/O error, dev mmcblk0, sector 2053
mmcblk0: error -84 sending status command, retrying
mmcblk0: error -84 sending status command, retrying
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: error -84 sending status command, retrying
mmcblk0: response CRC error sending r/w cmd command, card status 0x900
mmcblk0: error -84 sending status command, retrying
mmcblk0: error -84 sending status command, retrying
mmcblk0: error -84 sending status command, aborting
end_request: I/O error, dev mmcblk0, sector 1995
FAT-fs (mmcblk0): FAT read failed (blocknr 1995)
df: /mnt: Input/output error
发现能够正常的读写，好像一切都是没问题。
最后找到了原因，板子的SDIO做了兼容，既能够使用emmc，又能够使用TF卡，虽然连到TF卡上的电阻拿掉了，相当于断路，但是sdio的clk频率很大，有100M，多连接的导线相当于一个天线，会产生干扰。